An image forming method of a color electrophotographic method has become popular in a color composite apparatus for office use and a laser printer and expands to a color production printing market recently. Printed matters are sold as itself by small and medium printer makers in the color reproduction area, which is usually distinguished from the office use market. The demand to image characteristics such as color reproduction is severe since color tone of a merchandise photography relates to a sales amount directly.
JAPAN COLOR Reproduction Print 2001 is adopted as a standard color in the printing area, by which improves communication between print makers. Primary object for the electrophotographic image forming method has been to reproduce the JAPAN Color 2001, and major electrophotographic image forming apparatus manufactures are successful to cover the color reproduction area recently.
However, further expansion of color reproduction area is demanded by uses since an editing image on display is different from relatively narrow the CLOR JAPAN color reproduction area according to development of digital image input apparatus such as high specification digital camera or display technique.
This requires the accomplishment of color area and color reproduction of transparent display standard S-RGB, and for this purpose a new colorant is required. The S-RGB is a standard established by IEC (International Electrotechnical Commission) on October 0998. It is a representing formula to reproduce intended color regardless the species of personal computers, or display or printer machines. Particularly expansion of secondary chroma of green and blue area is required and new means to accomplish it is required.
While copper phthalocyanine colorant has been popular for cyan colorant, it is insufficient because of low chroma and transparency. Though a cyan dye is proposed as disclosed in Patent Document 1 to dissolve the problem, it is problematic in heat resistance, for example, there is observed color tone change in which blue is enhanced when fixing temperature raises.    Patent Document 1: JP A H11-212303